Background: Arthritis in Asian Americans: A Case Control Pilot Study of Knee Osteoarthritis, Physical Activity, and Ergonomic Exposures Among Chinese Outpatients in New York City: Specific Aims are: 1.Conduct a case control study among Chinese patients at Gouverneur Health Services in New York City to investigate hypotheses that onset of knee osteoarthritis is associated with history of self-reported occupational and non-occupational physical activities and ergonomic factors. 2. Construct a job exposure matrix for all jobs reported by subjects in the study and physical activities and ergonomic factors of interest using questionnaire data as well as information from the ergonomics and biomechanics literature.